An aneurysm is an abnormal local dilatation in the wall of a blood vessel, usually an artery, due to a defect, disease, or injury. One type of aneurysm is an intracranial aneurysm (IA). IAs have a risk of rupturing, which can result in a subarachnoid hemorrhage, a serious medical condition, often leading to severe neurological deficit or death.
A treatment goal of IAs is the prevention of rupture. Treatment methods can include two intervention options: clipping of the aneurysm neck and endovascular methods such as coiling and flow diversion. Traditionally, surgical clipping has been the treatment modality of choice for both ruptured and un-ruptured IAs; however, since the introduction of controlled detachable coils (GDC) for packing of aneurysms, endovascular aneurysm therapy has become an acceptable alternative to conventional neurosurgical treatment.
The technique of standard coil embolization can be limited by the shape of some of these aneurysms. For example, wide-necked aneurysms can be difficult to treat because of their unfavorable geometry, which can reduce the possibility of achieving dense packing and elimination of the aneurysm from circulation. One risk is the possibility of coil herniation through the broad neck into the parent vessel. This can cause thromboembolic events, which can be the most frequent and serious complications associated with endovascular treatment of intracranial aneurysms.
Various adjunctive techniques have been developed for the treatment of large, wide-neck and other complicated aneurysms. One technique is balloon-assisted treatment, in which a balloon is temporarily inflated across the aneurysm neck during coil insertion. In recent years, stents for intracranial use have become available, first as balloon-mounted stents and later as self-expandable stents with an open-cell or closed-cell design.